ADVANCE –Peglylated Avonex

Double Blind Study, placebo controlled

All subjects will receive one injection of either BIIB017 or a placebo every 2 weeks. Injections will be given for up to 2 years (96 weeks). During the first year, some subjects will only receive placebo but after the first year, all subjects will be receiving BIIB017. Pts have 66% chance of receiving drug.

Because BIIB017 is very similar to Avonex®, it is expected that the side effects of BIIB017 in people will be similar to what we have seen with Avonex.

Inclusion Criteria:

To be eligible to participate in this study, candidates must meet the following eligibility criteria at the time of randomization, Day 1:

1. Aged 18 to 55 years old, inclusive, at the time of informed consent.2. Must have a confirmed diagnosis of relapsing MS, as defined by MacDonald criteria3. Must have an EDSS score between 0.0 and 5.0.4. Must have experienced at least 2 relapses that have been medically documentedwithin the last 3 years with at least one of these relapses having occurred within thepast 12 months prior to randomization (Day 1).5. Subjects have refused alternative treatments and other available therapies.

Exlusion Criteria:

Medical History1. Primary progressive, secondary progressive, or progressive relapsing MS 2. Prior treatment with interferon cannot exceed 4 weeks and subjects must havediscontinued interferon treatment 6 months prior to Baseline.3. History of any clinically significant (as determined by the Investigator) cardiac,endocrinologic, hematologic, hepatic, immunologic, metabolic, urologic, pulmonary,neurologic, dermatologic, psychiatric, and renal, or other major disease that would preclude participation in a clinical trial.6. History of malignant disease, including solid tumors and hematologic malignancies (with the exception of basal cell and squamous cell carcinomas of the skin that have been completely excised and are considered cured).7. History of seizure disorder or unexplained blackouts OR history of a seizure within 3 months prior to Baseline.8. History of suicidal ideation within 3 months prior to Baseline or an episode of severe depression within 3 months prior to Baseline. Severe depression is defined as an episode of depression that requires hospitalization, or at the discretion of the Investigator.9. Clinically significant abnormal electrocardiogram (ECG) values as determined by the Investigator.10. Abnormal screening blood tests exceeding any of the limits defined below: • Alanine transaminase/serum glutamate pyruvate transaminase (ALT/SGPT) greater than 2 times the upper limit of normal (>2 × ULN) or aspartate transaminase/serum glutamic oxaloacetic transaminase (AST/SGOT) >2 × ULN or bilirubin >1.5 × ULN. • Total white blood cell count (WBC) < 3,700 /mm3 • Absolute Neutrophil Count (ANC) of < 1,500 /mm3 • Platelet count <150,000 c/mm3 • Hemoglobin <10 g/dL in female subjects; <11 g/dL in male subjects • Serum creatinine >ULN • Prothrombin time (PT) or activated partial thromboplastin time (aPTT) >1.2 × ULN11. An MS relapse that has occurred within the 50 days prior to randomization and/or thesubject has not stabilized from a previous relapse prior to randomization (Day 1).12. Elective surgery scheduled within 2 weeks of randomization (day 1)13.Treatment with other agents to treat MS symptoms or underlying disease as specified below: